Stakes are used extensively in the concrete construction trade. The stakes are commonly cylindrical in shape and made from metal, although other materials like wood or plastic may be used. When concrete is poured, it is in a semi-liquid state and forms are required to constrain the concrete to a desired shape or boundary. The stakes, which are typically driven into the ground with a sledgehammer, hold the forms in place while the concrete dries.
Once the concrete has hardened, the stakes must be pulled from the ground so the forms may be removed. Currently, this is a very laborious and time consuming task caused, primarily, by two factors. First, the stakes are driven deep into hard-packed soil, often to a depth of 30 inches or more. A great deal of physical effort is required to free the stake from the ground and, with the primitive tools currently available, it is often easier to simply abandon the stake by driving it below the ground's surface. The loss of stakes in this manner adds an additional penalty to an already costly process. Second, the large quantity of stakes required for the average construction project amplifies the stake removal problem. Even a small improvement over existing methods will add up to a significant time savings when several hundred stakes must be pulled.
Several patented devices attempt to solve the problems mentioned above, but all such devices are large, cumbersome, and unwieldy, and do not allow the application of all forces necessary for extraction. One such device is described in U.S. Pat. No. 6,302,376 to Williams, dated Oct. 16, 2001. The Williams patent depicts a device that relies on a fulcrum and lever arm to provide a mechanical advantage for easier removal of stakes. This device, however, does not lend itself well to removing concrete form stakes for several reasons. First, the overhang on the gripping end would interfere with the form. Second, the fulcrum rests on the ground, which is often uneven or littered with concrete that has spilled over the form, possibly rendering the device useless. Another example is U.S. Pat. No. 4,671,493 to Ravencroft, dated Jun. 9, 1987. This device uses a scissor action for gripping the stake, and a lever motion, utilizing the top of the form as its fulcrum, to pull the stake from the ground. The major drawback of this device, which the previous example also shares, is that several ratcheting/clamping motions are required before the stake is fully extracted from the ground. A better design would allow the stake to be pulled using a single fluid motion.
Other devices are intended to extract objects from the ground but, because they impart purely vertical motion to the object, do not function well, especially where concrete form stakes are involved. For example, U.S. Pat. No. 2,376,676 to Ferguson, dated May 22, 1945, describes an extractor tool with grippers that maintain their grip on an embedded object by means of serrated clamping jaws, where the serrations are situated parallel to the ground. This orientation of the serrations allows the grippers to maintain hold on the object while vertical force is being applied thereto, but is not well suited for maintaining a grip during the application of force from other directions. Another example occurs in U.S. Pat. No. 1,469,911 to Aumiller, dated Oct. 9, 1923. The Aumiller patent depicts and describes a pipe lifting implement wherein a pipe lifting device and a pipe supporting device both have serrated jaws that act, respectively, to lift the pipe vertically and to maintain the pipe in an elevated position. As with the Ferguson patent, the Aumiller patent does not show or describe a tool capable of imparting any force other than a vertical force—perpendicular to the ground—to the stake or other embedded object. Accordingly, a need exists for a tool capable of imparting both vertical and other forces to a stake or other embedded object, and to be capable of maintaining a firm grip on the object during the application of all such forces.